A former head of the Royal Navy has called for an end to the “disgrace” of soldiers facing prosecution over Troubles-era investigations in Northern Ireland.

Admiral Alan West said the next Conservative leader and prime minister must understand there is “no moral equivalence” between troops doing their duty and terrorists, and said he could not imagine how a fair trial can be held up to 45 years after an incident.

Addressing the Policy Exchange think tank in London on Thursday, Lord West said: “We have an absolute moral obligation [to the veterans] and I’m afraid we have not been fulfilling it.”

The former first sea lord added: “It is a disgrace that we are taking people through the courts in Northern Ireland. We really must move forward and do something.”

Author and Tory MP Tom Tugendhat, the chair of the foreign affairs select committee at Westminster, said it was “a sad indictment” of successive Conservative defence secretaries that “the government has achieved almost nothing” in terms of protecting troops from prosecution.

The Policy Exchange event on ‘Lawfare’ had been organised in response to “the actions of our troops being challenged in court as never before,” and to “consider a series of novel and bold policy proposals the next government should adopt”.

There are currently a number of former soldiers facing prosecution over Troubles-related fatalities, including ‘Soldier F’ who is accused of murdering two men in Londonderry in 1972 on what became known as Bloody Sunday.

Policy Exchange director Dean Godson paid tribute to those working to amend the laws, and the approach of government, to ensure that “British forces are afforded the protection they deserve, for past operations, for present and future operations”.

Paraphrasing a quote from Lt General Sir Paul Newton, Mr Godson said: “There is no such thing as a historical inquiry. Every historical inquiry has a direct impact on the mind set and thinking and culture of present-day troops, who are left wondering if they will be facing similar investigations, inquests and lawsuits.”

Among those proposing major changes to legislation is Richard Ekins, associate professor at the University of Oxford.

He said the next Tory leader “should introduce new legislation to the Commons to amend the Human Rights Act 1998, and should also introduce legislation bringing to an end, or at least sharply curtailing, the legal legacy of the Troubles”.